My wifes 00 expedition starter was grinding every 4th or 5th start, so I changed the starter with a NAPA starter thinking that the starter was bad. I still have the same problem. Every now and then, when I try to start the vehicle it seems like the starter is missing the teeth on the flywheel and grinds real loud. I turn the key back and try it again and it starts up fine. She tells me that this does it about every 4th or 5th time she starts it. I was told by a person the the expedition flywheel only has about three spots on the flywheel that will engage the starter. I do not know how true this is, as most flywheels I've seen have always had teeth all the way around them.

 

You probably just need a new battery or have dirty or loose connection at the battery.

 

Battery was new last year, and the terminals were cleaned when I changed the starter.

 

Possibilities. Got a bad starter from Napa, or the ring gear on the flywheel is getting bad. I would still check all connections at the battery and make sure they are clean and tight, espeacially the ground. I would double check the connections at the starter, make sure they are clean and tight. Sometimes loose or corroided connections can cause these symptoms.

 

Maybe off the mark, but check the integrity of the ht lead - the big fat red one - that feeds the starter. I had one go bad when salt and water breached the sheath rotting it from the inside. Symptom when it's on it's last copper thread was similar to low battery/bad connection.

The 'bad' part may be hard to locate without removing - I didn't bother. My final check confirm the diagnosis was to temporarily attach a battery jumper cable to provide power to the starter. That done, I just chopped off what I could access of the old one and threaded a new one in an easier route...